NASCIMENTO, Camila Tauane Monteiro do. Expressão heteróloga de uma osmotina laticífera e desenvolvimento de protocolos para extração da proteína recombinante a partir de corpos de inclusão. 2016. 93 f. Dissertação (Mestrado em Bioquímica)-Universidade Federal do Ceará, Fortaleza-CE, 2016. / Submitted by Eric Santiago (erichhcl@gmail.com) on 2016-07-19T15:11:48Z No. of bitstreams: 1 2016_dis_ctmnascimento.pdf: 2987876 bytes, checksum: d61b36bc9503e63cca6a1c604887ad09 (MD5) / Approved for entry into archive by José Jairo Viana de Sousa (jairo@ufc.br) on 2016-08-02T20:31:41Z (GMT) No. of bitstreams: 1 2016_dis_ctmnascimento.pdf: 2987876 bytes, checksum: d61b36bc9503e63cca6a1c604887ad09 (MD5) / Made available in DSpace on 2016-08-02T20:31:41Z (GMT). No. of bitstreams: 1 2016_dis_ctmnascimento.pdf: 2987876 bytes, checksum: d61b36bc9503e63cca6a1c604887ad09 (MD5) Previous issue date: 2016 / In the previous step to this work, a protein identified as osmotin (CpOsm) was purified from Calotropis procera latex which showed strong antifungal activity. The protein was expressed in prokaryotic and eukaryotic systems, but a suitable protocol for purification has not been achieved. In the present work, from inclusion bodies (IB) obtained from Escherichia coli BL21 (DE3) proceeded to a survey by different solubilization protocols of proteins in an attempt to obtain the recombinant protein (rCpOsm) soluble, and then evaluates it as its activity and finally, exploring new methods for purification. The bacterial culture was induced at different conditions of temperature and time of induction. IB were subjected to chemical treatments with surfactants (CTAB; Cetrimide; ARG-12, a derivative surfactant Argenine) and a denaturing agent (guanidine hydrochloride); physical treatment by sonication and the enzymatic treatment with protease native C. procera latex. Electrophoresis assays suggested that two chemical surfactants were effective in solubilizing rCpOsm while not ARG-12. Although these cationic compounds solubilized rCpOsm more than other proteins of IB, while the sonication process samples produced with a greater variety of soluble proteins including rCpOsm. The enzymatic treatment showed that IB proteins are, in some range, digested while rCpOsm did not. All samples were evaluated for action on Colletotrichum gloeosporiodes after dialysis and lyophilization and showed inhibitory activity of spore germination and mycelial growth. However, it was shown that the activity could be related to the solubilising agents. Insoluble proteins obtained from E. coli containing the plasmid integrity, taken as a negative control showed no activity in these assays. The rCpOsm solubilized by CTAB was subjected to chromatography on Ni ++ column (Ni Sepharose 6 Fast Flow) pH 7.0; in hydrophobic media (FenilSepharose CL-4B) and ion exchange (Resource-S). None of the applied protocols resulted in the purification of rCpOsm and these data repeated what was observed previously for rCpOsm purified from Pichia pastoris. / Em etapa anterior a este trabalho, uma proteína identificada como osmotina (CpOsm) foi purificada do látex de Calotropis procera a qual apresentou forte atividade antifúngica. A proteína foi expressa em sistemas procarionte e eucarionte, mas um protocolo adequado para sua purificação não foi alcançado. No presente trabalho, partindo de corpos de inclusão (CI), obtidos de E. coli BL21(DE3) procedeu-se uma prospecção por diferentes protocolos de solubilização de suas proteínas, na tentativa de obter a proteína recombinante (rCpOsm) solúvel, para então avaliá-la quanto a sua atividade e por fim, prospectar novos métodos para sua purificação. A cultura bacteriana foi induzida em diferentes condições de temperatura e tempo de indução. Após 3 horas de indução a 37 °C, 180 rpm, os CI foram lisados e submetidos a tratamentos químicos com surfactantes (CTAB; Cetrimida; ARG-12: um surfactante derivado de argenina) e um agente desnaturante (Cloridrato de Guanidina); tratamento físico por sonicação (4 ciclos de 2,5 min. cada a 50% de potência) e tratamento enzimático com protease nativa do látex de C. procera. Ensaios de eletroforese sugeriram que os dois surfactantes químicos foram eficientes na solubilização de rCpOsm enquanto que ARG-12 não. Ainda, estes compostos catiônicos solubilizaram rCpOsm mais do que as demais proteínas dos CI, enquanto que o processo de sonicação produziu amostras com maior diversidade de proteínas solúveis, incluindo rCpOsm. O tratamento enzimático mostrou que proteínas de CI são, em algum alcance, digeridas enquanto que rCpOsm não. O efeito do tratamento dos CI com protease foi analisado por imagens de microscopia de força atômica e as diferenças de estrutura entre os CI tratados e não tratados documentados. Todas as amostras foram avaliadas quanto à ação sobre Colletotrichum gloeosporiodes após diálise e liofilização. Os produtos dos tratamentos com surfactantes apresentaram atividade antifúngica, demonstrando atividade inibitória de germinação de esporos e crescimento micelial. Entretanto, foi demonstrado que a atividade poderia estar relacionada aos agentes solubilizantes. Proteínas insolúveis obtidas de E. coli contendo o plasmídeo íntegro, tomadas como controle negativo, não apresentaram atividade nestes ensaios. A rCpOsm solubilizada com CTAB foi submetida a cromatografia em coluna de Ni++ (Ni Sepharose 6 Fast Flow) pH 7,0; em meio hidrofóbico (FenilSepharose CL-4B) e troca iônica (Resource-S). Nenhum dos protocolos aplicados resultou na purificação de rCpOsm e estes dados repetem o que foi observado previamente para a rCpOsm purificada a partir de Pichia pastoris.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / In the previous step to this work, a protein identified as osmotin (CpOsm) was purified from Calotropis procera latex which showed strong antifungal activity. The protein was expressed in prokaryotic and eukaryotic systems, but a suitable protocol for purification has not been achieved. In the present work, from inclusion bodies (IB) obtained from Escherichia coli BL21 (DE3) proceeded to a survey by different solubilization protocols of proteins in an attempt to obtain the recombinant protein (rCpOsm) soluble, and then evaluates it as its activity and finally, exploring new methods for purification. The bacterial culture was induced at different conditions of temperature and time of induction. IB were subjected to chemical treatments with surfactants (CTAB; Cetrimide; ARG-12, a derivative surfactant Argenine) and a denaturing agent (guanidine hydrochloride); physical treatment by sonication and the enzymatic treatment with protease native C. procera latex. Electrophoresis assays suggested that two chemical surfactants were effective in solubilizing rCpOsm while not ARG-12. Although these cationic compounds solubilized rCpOsm more than other proteins of IB, while the sonication process samples produced with a greater variety of soluble proteins including rCpOsm. The enzymatic treatment showed that IB proteins are, in some range, digested while rCpOsm did not. All samples were evaluated for action on Colletotrichum gloeosporiodes after dialysis and lyophilization and showed inhibitory activity of spore germination and mycelial growth. However, it was shown that the activity could be related to the solubilising agents. Insoluble proteins obtained from E. coli containing the plasmid integrity, taken as a negative control showed no activity in these assays. The rCpOsm solubilized by CTAB was subjected to chromatography on Ni ++ column (Ni Sepharose 6 Fast Flow) pH 7.0; in hydrophobic media (FenilSepharose CL-4B) and ion exchange (Resource-S). None of the applied protocols resulted in the purification of rCpOsm and these data repeated what was observed previously for rCpOsm purified from Pichia pastoris. / Em etapa anterior a este trabalho, uma proteÃna identificada como osmotina (CpOsm) foi purificada do lÃtex de Calotropis procera a qual apresentou forte atividade antifÃngica. A proteÃna foi expressa em sistemas procarionte e eucarionte, mas um protocolo adequado para sua purificaÃÃo nÃo foi alcanÃado. No presente trabalho, partindo de corpos de inclusÃo (CI), obtidos de E. coli BL21(DE3) procedeu-se uma prospecÃÃo por diferentes protocolos de solubilizaÃÃo de suas proteÃnas, na tentativa de obter a proteÃna recombinante (rCpOsm) solÃvel, para entÃo avaliÃ-la quanto a sua atividade e por fim, prospectar novos mÃtodos para sua purificaÃÃo. A cultura bacteriana foi induzida em diferentes condiÃÃes de temperatura e tempo de induÃÃo. ApÃs 3 horas de induÃÃo a 37 ÂC, 180 rpm, os CI foram lisados e submetidos a tratamentos quÃmicos com surfactantes (CTAB; Cetrimida; ARG-12: um surfactante derivado de argenina) e um agente desnaturante (Cloridrato de Guanidina); tratamento fÃsico por sonicaÃÃo (4 ciclos de 2,5 min. cada a 50% de potÃncia) e tratamento enzimÃtico com protease nativa do lÃtex de C. procera. Ensaios de eletroforese sugeriram que os dois surfactantes quÃmicos foram eficientes na solubilizaÃÃo de rCpOsm enquanto que ARG-12 nÃo. Ainda, estes compostos catiÃnicos solubilizaram rCpOsm mais do que as demais proteÃnas dos CI, enquanto que o processo de sonicaÃÃo produziu amostras com maior diversidade de proteÃnas solÃveis, incluindo rCpOsm. O tratamento enzimÃtico mostrou que proteÃnas de CI sÃo, em algum alcance, digeridas enquanto que rCpOsm nÃo. O efeito do tratamento dos CI com protease foi analisado por imagens de microscopia de forÃa atÃmica e as diferenÃas de estrutura entre os CI tratados e nÃo tratados documentados. Todas as amostras foram avaliadas quanto à aÃÃo sobre Colletotrichum gloeosporiodes apÃs diÃlise e liofilizaÃÃo. Os produtos dos tratamentos com surfactantes apresentaram atividade antifÃngica, demonstrando atividade inibitÃria de germinaÃÃo de esporos e crescimento micelial. Entretanto, foi demonstrado que a atividade poderia estar relacionada aos agentes solubilizantes. ProteÃnas insolÃveis obtidas de E. coli contendo o plasmÃdeo Ãntegro, tomadas como controle negativo, nÃo apresentaram atividade nestes ensaios. A rCpOsm solubilizada com CTAB foi submetida a cromatografia em coluna de Ni++ (Ni Sepharose 6 Fast Flow) pH 7,0; em meio hidrofÃbico (FenilSepharose CL-4B) e troca iÃnica (Resource-S). Nenhum dos protocolos aplicados resultou na purificaÃÃo de rCpOsm e estes dados repetem o que foi observado previamente para a rCpOsm purificada a partir de Pichia pastoris.

Flavonoids are plant secondary metabolites well known for many key roles in the life cycle of plants. They also can affect human health. Citrus paradisi is known to produce several glucosylated flavonoids and these compounds are glucosylated by enzymes known as glucosyltransferases (GTs). The focus of this research was to optimize the heterologous expression, enrichment, and biochemical characterization of grapefruit putative GT protein, PGT2, and to test the hypothesis that PGT2 is a flavonoid GT. Results showed detectable amounts of activity with quercetin, a flavonol; however, activity was lower than what would be expected if this enzyme were a flavonol-specific GT. In an additional aspect of this study, bioinformatics were used to test the hypothesis that additional putative GT clones could be identified using the harvEST database.

Lam Wun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 140-153). / Abstracts in English and Chinese. / ABSTRACT --- p.i / ACKNOWLDGEMENT --- p.iii / TABLE OF CONTENT --- p.iv / ABBREVIATIONS --- p.x / LISTS OF TABLES --- p.xi / LISTS OF FIGURES --- p.xii / Chapter 1. --- INTRODUCTION / Chapter 1.1 --- Neurodegeneration and triplet repeat diseases --- p.1 / Chapter 1.2 --- Polyglutamine diseases --- p.2 / Chapter 1.3 --- Polyglutamine nuclear inclusions --- p.4 / Chapter 1.3.1 --- Kinetics of polyglutamine nuclear inclusion formation --- p.4 / Chapter 1.3.2 --- Roles of protein inclusions in neurodegeneration --- p.7 / Chapter 1.4 --- Polyglutamine pathogenic pathways --- p.8 / Chapter 1.4.1 --- Protein depletion theory --- p.9 / Chapter 1.4.2 --- Induction of apoptotic pathways --- p.13 / Chapter 1.5 --- Previous study on NI proteins --- p.14 / Chapter 1.6 --- Drosophila model for studying polyglutamine diseases --- p.15 / Chapter 1.6.1 --- Drosophila model for studying human diseases --- p.15 / Chapter 1.6.2 --- GAL4/UAS gene expression system --- p.15 / Chapter 1.6.3 --- Drosophila polyglutamine models --- p.17 / Chapter 1.7 --- Objectives of the study --- p.21 / Chapter 2. --- MATERIALS AND METHODS / Chapter 2.1 --- Drosophila genetics --- p.22 / Chapter 2.1.1 --- Drosophila culture --- p.22 / Chapter 2.1.2 --- GAL4/UAS gene expression system --- p.22 / Chapter 2.1.3 --- Eye phenotypic analysis --- p.25 / Chapter 2.1.4 --- Polyglutamine fly models --- p.25 / Chapter 2.1.5 --- Generation and characterization of GFP-polyglutamine transgenic fly models --- p.25 / Chapter 2.2 --- Proteomic identification of nuclear inclusion proteins --- p.26 / Chapter 2.2.1 --- Proteomic identification of NI proteins by SDS-insolubility of NIs --- p.26 / Chapter 2.2.2 --- Proteomic identification of NI proteins by FA-solubility of NIs --- p.27 / Chapter 2.2.2.1 --- Approach overview --- p.27 / Chapter 2.2.2.2 --- Sample preparation for two-dimensional gel electrophoresis --- p.27 / Chapter 2.2.2.3 --- Two-dimensional gel electrophoresis --- p.29 / Chapter 2.2.2.4 --- Polyacrylamide gel staining --- p.31 / Chapter 2.2.2.5 --- Computer analysis of 2D patterns --- p.31 / Chapter 2.2.2.6 --- In-gel trypsin digestion --- p.32 / Chapter 2.2.2.7 --- Mass spectrometric analysis --- p.33 / Chapter 2.2.3 --- Detection of NIs by flow cytometry --- p.34 / Chapter 2.3 --- SDS-polyacrylamide gel electrophoresis (SDS-PAGE) --- p.34 / Chapter 2.3.1 --- Sample preparation for SDS-PAGE --- p.34 / Chapter 2.3.2 --- SDS-PAGE --- p.35 / Chapter 2.4 --- Immunodetection --- p.36 / Chapter 2.4.1 --- Electroblotting --- p.36 / Chapter 2.4.2 --- Western blotting --- p.36 / Chapter 2.4.3 --- Filter trap assay --- p.37 / Chapter 2.5 --- Sav antibody production --- p.38 / Chapter 2.5.1 --- Sav peptide synthesis --- p.38 / Chapter 2.5.2 --- Rabbit immunization --- p.38 / Chapter 2.6 --- Cryosectioning and immunostaining of adult fly heads --- p.39 / Chapter 2.7 --- Alcohol dehydrogenase assay --- p.40 / Chapter 2.8 --- Semi-quantitative reverse transcription- Polymerase Chain Reaction --- p.41 / Chapter 2.8.1 --- Total RNA preparation from fly heads --- p.41 / Chapter 2.8.2 --- Reverse transcription- Polymerase Chain Reaction (RT-PCR) --- p.41 / Chapter 2.9 --- Reagents and buffers --- p.42 / Chapter 3. --- RESULTS / Chapter 3.1 --- Transgenic polyglutamine fly models --- p.48 / Chapter 3.1.1 --- Characteristics of MJD polyglutamine fly model --- p.48 / Chapter 3.1.1.1 --- Overexpression of expanded truncated human MJD proteins in Drosophila causes eye degeneration --- p.49 / Chapter 3.1.1.2 --- Overexpression of expanded truncated human MJD proteins in Drosophila results in nuclear inclusion formation --- p.49 / Chapter 3.1.1.3 --- Formic acid dissolves fly polyglutamine nuclear inclusions --- p.51 / Chapter 3.1.1.3.1 --- Formic acid dissolves fly polyglutamine NIs as shown by Western blot analysis --- p.51 / Chapter 3.1.1.3.2 --- Formic acid dissolves fly polyglutamine NIs as shown by filter trap assay --- p.53 / Chapter 3.1.2 --- Summary --- p.55 / Chapter 3.2 --- Proteomic identification of nuclear inclusion (NI) proteins --- p.56 / Chapter 3.2.1 --- Proteomic identification of NI proteins by SDS-insolubility of NIs --- p.56 / Chapter 3.2.2 --- Proteomic identification of NI proteins by FA-solubility of NIs --- p.63 / Chapter 3.2.2.1 --- Two-dimensional gels showing differential protein spots as potential NI proteins --- p.63 / Chapter 3.2.2.2 --- NI protein candidates identified by the 2D approach --- p.75 / Chapter 3.2.3 --- Study of polyglutamine NI proteins by flow cytometry analysis --- p.90 / Chapter 3.2.3.1 --- Detection of fly polyglutamine NIs by flow cytometry --- p.90 / Chapter 3.2.3.2 --- Characterization of a new GFP-polyglutamine fly model --- p.92 / Chapter 3.3 --- Characterization of the nuclear inclusion protein candidates --- p.96 / Chapter 3.3.1 --- Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) --- p.96 / Chapter 3.3.1.1 --- Confirmation of GAPDH as a NI protein --- p.97 / Chapter 3.3.1.2 --- Discussion --- p.97 / Chapter 3.3.2 --- Receptor of activated protein kinase C (RACK1) --- p.99 / Chapter 3.3.2.1 --- Confirmation of RACK1 as a NI protein --- p.99 / Chapter 3.3.2.1.1 --- Colocalization of RACK1 with NIs --- p.99 / Chapter 3.3.2.1.2 --- Formic Acid extracts RACK1 from NIs --- p.101 / Chapter 3.3.2.2 --- Reduction of soluble RACK1 protein level in polyglutamine fly --- p.101 / Chapter 3.3.2.2.1 --- Soluble RACK1 protein level reduced in polyglutamine fly --- p.101 / Chapter 3.3.2.2.2 --- RACK1 transcript level remains unchanged in polyglutamine fly --- p.103 / Chapter 3.3.2.3 --- Overexpression of RACK 1 partially suppresses polyglutamine degeneration --- p.105 / Chapter 3.3.2.4 --- Discussion --- p.107 / Chapter 3.3.3 --- Warts (Wts) --- p.111 / Chapter 3.3.3.1 --- Overexpression of Wts partially suppresses polyglutamine degeneration --- p.111 / Chapter 3.3.3.2 --- Wts mutant slightly enhances polyglutamine degeneration --- p.113 / Chapter 3.3.3.3 --- Genetic analysis of Warts pathway in polyglutamine pathogenesis --- p.113 / Chapter 3.3.3.3.1 --- Overexpression of Salvador partially suppresses polyglutamine degeneration --- p.116 / Chapter 3.3.3.3.2 --- Hpo mutant slightly enhances polyglutamine degeneration --- p.119 / Chapter 3.3.3.3.3 --- Overexpression of DIAP1 partially suppresses polyglutamine degeneration --- p.119 / Chapter 3.3.3.4 --- Discussion --- p.121 / Chapter 3.3.4 --- Alcohol dehydrogenase (Adh) --- p.122 / Chapter 3.3.4.1 --- Adh activity is reduced in polyglutamine flies --- p.122 / Chapter 3.3.4.2 --- Overexpression of Hsp70 partially restores the reduced Adh activity in polyglutamine flies --- p.122 / Chapter 3.3.4.3 --- Discussion --- p.125 / Chapter 3.3.5 --- Genetic analysis of other NI protein candidates --- p.127 / Chapter 3.3.5.1 --- Overexpression of CG7920 protein partially suppresses polyglutamine degeneration --- p.127 / Chapter 3.3.5.2 --- Pten dsRNA slightly enhances polyglutamine degeneration --- p.129 / Chapter 3.3.6 --- Summary --- p.131 / Chapter 4. --- DISSCUSSION / Chapter 4.1 --- Protein depletion theory --- p.133 / Chapter 4.2 --- Comparison of different approaches for identification of NI proteins --- p.134 / Chapter 4.3 --- Long-term significance --- p.136 / Chapter 4.4 --- Future studies --- p.137 / Chapter 4.4.1 --- Characterization of other NI protein candidates --- p.137 / Chapter 4.4.2 --- Study of NI proteins by an alternative approach --- p.137 / Chapter 4.4.3 --- Study of NI proteins using other polyglutamine fly models --- p.137 / Chapter 5. --- CONCLUSION --- p.139 / Chapter 6. --- REFERENCES --- p.140

As principais matérias primas necessárias para a preparação de testes diagnósticos são as proteínas dos patógenos que necessariamente apresentem as estruturas nativas. O objetivo do presente estudo foi a obtenção das proteínas não estruturais 1 (NS1) dos vírus da dengue (DENV) e da zika (ZIKV) a partir dos corpúsculos de inclusão (CI) produzidos em bactérias Escherichia coli. Mostramos que a combinação de alta pressão hidrostática (APH) e pH alcalino é eficiente para a solubilização de NS1-CI. A incubação em 2,4 kbar das suspensões de NS1-CI em pH alcalino mostrou-se eficiente para a solubilização da NS1. A presença de Arg promove a dissociação de oligômeros. A aplicação de 2,4 kbar às suspensões de NS1-CI em pH de 10,5 (DENV) e de 11,5 (ZIKV) na presença de Arg e um par redox, seguida de diálise em tampão em pH 8,5, foram as condições escolhidas para o reenovelamento de NS1. Obtivemos ambas NS1 com rendimentos entre 75% e 90% em relação às quantidades totais das proteínas presente nos correspondentes CI de NS1. As NS1 reenoveladas apresentaram reatividade comparável às proteínas obtidas utilizando um protocolo convencional estabelecido, com rendimentos mais de 25 vezes superiores. Foi obtido um processo altamente eficiente para o reenovelamento de NS1 apresentando características biológicas preservadas em relação a reatividade com anticorpos específicos de antígeno, incluindo soro de paciente infectado com zikv e que, portanto, podem ser usados como antígeno para o desenvolvimento de vacinas ou testes de diagnóstico. Além disso, este estudo descreve a criação de um processo inovador, que é a utilização concomitante de APH e pH alcalino, para solubilização e posterior reenovelamento de NS1-CI que podem ser utilizados para outras proteínas relevantes. / The main products for the preparation of diagnostic tests are as proteins of the pathogens that necessarily present as the native structures. The objective of the present study was to obtain non-structural proteins 1 (NS1) from dengue virus (DENV) and zika virus (ZIKV) from the inclusion bodies (IBs) produced in Escherichia coli bacteria. We show that it is a combination of high hydrostatic pressure (HHP) and alkaline pH is efficient for a solubilization of NS1-IB. A 2.4 kbar incubation of NS1-IB suspensions at alkaline pH proved to be efficient for NS1 solubilization. The presence of Arg promotes the dissociation of oligomers. The application of 2.4 kbar to the suspensions of NS1-IB at pH 10.5 (DENV) and 11.5 (ZIKV) in the presence of Arg and a redox pair, dialysis in pH 8.5 buffer were as conditions chosen for the refolding of NS1. We obtained both NS1 at yields between 75% and 90% relative to the total amounts of the proteins present in the corresponding NS1 IB. Refolded NS1 showed similar to proteins obtained using an established standard protocol, with yields more than 25 times higher. A highly efficient process for the refolding of NS1 was obtained with preserved biological features regarding reactivity with antigen-specific antibodies, including sera of zikv-infected patients and that can be used as antigen for the development of vaccines or diagnostic tests. In addition, this study describes the creation of an innovative process, which is a concomitant use of HHP and alkaline pH, for solubilization and subsequent refolding of NS1-IB that can be used for other relevant proteins.

As principais matérias primas necessárias para a preparação de testes diagnósticos são as proteínas dos patógenos que necessariamente apresentem as estruturas nativas. O objetivo do presente estudo foi a obtenção das proteínas não estruturais 1 (NS1) dos vírus da dengue (DENV) e da zika (ZIKV) a partir dos corpúsculos de inclusão (CI) produzidos em bactérias Escherichia coli. Mostramos que a combinação de alta pressão hidrostática (APH) e pH alcalino é eficiente para a solubilização de NS1-CI. A incubação em 2,4 kbar das suspensões de NS1-CI em pH alcalino mostrou-se eficiente para a solubilização da NS1. A presença de Arg promove a dissociação de oligômeros. A aplicação de 2,4 kbar às suspensões de NS1-CI em pH de 10,5 (DENV) e de 11,5 (ZIKV) na presença de Arg e um par redox, seguida de diálise em tampão em pH 8,5, foram as condições escolhidas para o reenovelamento de NS1. Obtivemos ambas NS1 com rendimentos entre 75% e 90% em relação às quantidades totais das proteínas presente nos correspondentes CI de NS1. As NS1 reenoveladas apresentaram reatividade comparável às proteínas obtidas utilizando um protocolo convencional estabelecido, com rendimentos mais de 25 vezes superiores. Foi obtido um processo altamente eficiente para o reenovelamento de NS1 apresentando características biológicas preservadas em relação a reatividade com anticorpos específicos de antígeno, incluindo soro de paciente infectado com zikv e que, portanto, podem ser usados como antígeno para o desenvolvimento de vacinas ou testes de diagnóstico. Além disso, este estudo descreve a criação de um processo inovador, que é a utilização concomitante de APH e pH alcalino, para solubilização e posterior reenovelamento de NS1-CI que podem ser utilizados para outras proteínas relevantes. / The main products for the preparation of diagnostic tests are as proteins of the pathogens that necessarily present as the native structures. The objective of the present study was to obtain non-structural proteins 1 (NS1) from dengue virus (DENV) and zika virus (ZIKV) from the inclusion bodies (IBs) produced in Escherichia coli bacteria. We show that it is a combination of high hydrostatic pressure (HHP) and alkaline pH is efficient for a solubilization of NS1-IB. A 2.4 kbar incubation of NS1-IB suspensions at alkaline pH proved to be efficient for NS1 solubilization. The presence of Arg promotes the dissociation of oligomers. The application of 2.4 kbar to the suspensions of NS1-IB at pH 10.5 (DENV) and 11.5 (ZIKV) in the presence of Arg and a redox pair, dialysis in pH 8.5 buffer were as conditions chosen for the refolding of NS1. We obtained both NS1 at yields between 75% and 90% relative to the total amounts of the proteins present in the corresponding NS1 IB. Refolded NS1 showed similar to proteins obtained using an established standard protocol, with yields more than 25 times higher. A highly efficient process for the refolding of NS1 was obtained with preserved biological features regarding reactivity with antigen-specific antibodies, including sera of zikv-infected patients and that can be used as antigen for the development of vaccines or diagnostic tests. In addition, this study describes the creation of an innovative process, which is a concomitant use of HHP and alkaline pH, for solubilization and subsequent refolding of NS1-IB that can be used for other relevant proteins.

HTML clipboard The great advances in DNA technology, e.g. sequencing and recombinant DNA techniques, have given us the genetic information and the tools needed to effectively produce recombinant proteins. Recombinant proteins are valuable means in biotechnological applications and are also emerging as alternatives in therapeutic applications. Traditionally, monoclonal antibodies have been the natural choice for biotechnological and therapeutic applications due to their ability to bind a huge range of different molecules and their natural good affinity. However, the large size of antibodies (150 kDa) limits tissue penetration and the recombinant expression is complicated. Therefore, alternative binders with smaller sizes have been derived from antibodies and alternative scaffolds. In this thesis, two structurally similar domains, Zbasic and ABDz1, have been used as purification tags in different contexts. They are both three-helical bundles and derived from bacterial surface domains, but share no sequence homology. Furthermore, by redesign of the scaffold used for ABDz1, a molecule intended for drug targeting with extended in-vivo half-life has been engineered. In Papers I and II, the poly-cationic tag Zbasic is explored and evaluated. Paper I describes the successful investigation of Zbasic as a purification handle under denaturating conditions. Moreover, Zbasic is evaluated as an interaction domain in matrixassisted refolding. Two different proteins were successfully refolded using the same setup without individual optimization. In Paper II, Zbasic is further explored as a purification handle under non-native conditions in a multi-parallel setup. In total, 22 proteins with varying characteristics are successfully purified using a multi-parallel protein purification protocol and a robotic system. Without modifications, the system can purify up to 60 proteins without manual handling. Paper I and II clearly demonstrate that Zbasic can be used as an interaction domain in matrix-assisted refolding and that it offers a good alternative to the commonly used His6-tag under denaturating conditions. In paper III, the small bifunctional ABDz1 is selected from a phage display library. Endowed with two different binding interfaces, ABDz1 is capable of binding both the HSA-sepharose and the protein A-derived MabSelect SuRe-matrix. The bifunctionality of the domain is exploited in an orthogonal affinity setup. Three target proteins are successfully purified using the HSA-matrix and the MabSelect SuRe-matrix. Furthermore, the purity of the target proteins is effectively improved by combining the two chromatographic steps. Thus, paper III shows that the small ABDz1 can be used as an effective purification handle and dual affinity tag without target specific optimization. Paper IV describes the selection and affinity maturation of small bispecific drug-targeting molecules. First generation binders against tumor necrosis factor-α are selected using phage display. Thereafter on-cell surface display and flow cytometry is used to select second-generation binders. The binding to tumor necrosis factor-α is improved up to 30 times as compared to the best first generation binder, and a 6-fold improvement of the binding strength was possible with retained HSA affinity. Paper III and IV clearly demonstrate that dual interaction surfaces can successfully be grafted on a small proteinaceous domain, and that the strategy in paper IV can be used for dual selection of bifunctional binders. / <p>QC20100610</p>

The overall objective of this work has been to adopt new developments and techniques in the area of measurement, modelling and control of fermentation processes. Flow cytometry and software sensors are techniques which were considered ready for application and the focus was set on developing tools for research aiming at understanding the relationship between measured variables and process quality parameters. In this study fed-batch cultivations have been performed with two different strains of Escherichia coli (E.coli) K12 W3110 with and without a gene for the recombinant protein promegapoietin. Inclusion body formation was followed during the process with flow cytometric detection by labelling the inclusion bodies with first an antibody against the protein promegapoietin and then a second fluorescent anti-antibody. The approach to label inclusion bodies directly in disintegrated and diluted cell slurry could be adopted as a method to follow protein production during the process, although the labelling procedure with incubation times and washings was somewhat time-consuming (1.5 h). The labelling of inclusion bodies inside the cells to follow protein production was feasible to perform, although an unexplained decrease in the relative fluorescence intensity occurred late in process. However, it is difficult to translate this qualitative measurement into a quantitative one, since a quantitative protein analysis should give data proportional to the volume, while the labelling of the spheric inclusion bodies gives a signal corresponding to the area of the body, and calibration is not possible. The methods were shown to be useful for monitoring inclusion body formation, but it seems difficult to get quantitative information from the analysis. Population heterogeneity analysis was performed, by using flow cytometry, on a cell population, which lost 80-90% viability according to viable count analysis. It was possible to show that the apparent cell death was due to cells incapable of dividing on agar plates after induction. These cells continued to produce the induced recombinant protein. It was shown that almost all cells in the population (≈97%) contained PMP, and furthermore total protein analysis of the medium indicated that only about 1% of the population had lysed. This confirms that the "non-viable" cells according to viable count by cfu analysis produced product. The software sensors XNH3 and µNH3, which utilises base titration data to estimate biomass and specific growth rate was shown to correlate well with the off-line analyses during cultivation of E. coli W3110 using minimal medium. In rich medium the µNH3 sensor was shown to give a signal that may be used as a fingerprint of the process, at least from the time of induction. The software sensor KLaC* was shown to respond to foaming in culture that probably was caused by increased air bubble dispersion. The RO/S coefficient, which describes the oxygen to substrate consumption, was shown to give a distinct response to stress caused by lowered pH and addition of the inducing agent IPTG. The software sensor for biomass was applied to a highly automated 6-unit multi-bioreactor system intended for fast process development. In this way also specific rates of substrate and oxygen consumption became available without manual sampling. / QC 20100819

The successful genomic era has resulted in a great demand for efficient production and purification of proteins. The main objective of the work described in this thesis was to develop methods to facilitate recovery of target proteins after recombinant production in Escherichia coli. A positively charged purification tag, Zbasic, has previously been constructed by protein design of a compact three-helix bundle domain, Z. The charged domain was investigated for general use as a fusion partner. All target proteins investigated could be selectively captured by ion-exchange chromatography under conditions excluding adsorption of the majority of Escherichia coli host proteins. A single cation-exchange chromatography step at physiological pH was sufficient to provide Zbasic fusion proteins of high purity close to homogeneity. Moreover, efficient isolation directly from unclarified Escherichia coli homogenates could also be accomplished using an expanded bed mode. Since the intended use of a recombinant protein sometimes requires removal of the purification tag, a strategy for efficient release of the Zbasic moiety using an immobilised protease was developed. The protease columns were reusable without any measurable decrease in activity. Moreover, subsequent removal of the released tag, Zbasic, was effected by adsorption to a second cation-exchanger. Using a similar strategy, a purification tag with a negatively charged surface, denoted Zacid, was constructed and thoroughly characterised. Contrary to Zbasic, the negatively charged Zacid was highly unstructured in a low conductivity environment. Despite this, all Zacid fusion proteins investigated could be efficiently purified from whole cell lysates using anion-exchange chromatography Synthesis of polypeptides occurs readily in Escherichia coli providing large amounts of protein in cells of this type, albeit often one finds the recombinant proteins sequestered in inclusion bodies. Therefore, a high throughput method for screening of protein expression was developed. Levels of both soluble and precipitated protein could simultaneously be assessed in vivo by the use of a flow cytometer. The positively charged domain, Zbasic, was shown also to be selective under denaturing conditions, providing the possibility to purify proteins solubilised from inclusion bodies. Finally, a flexible process for solid-phase refolding was developed, using Zbasic as a reversible linker to the cation-exchanger resin. / QC 20101020

The versatile Escherichia coli facilitates protein expression with relative simplicity, high cell density on inexpensive substrates, well known genetics, variety of expression vectors, mutant strains, co-overexpression technology, extracytoplasmic secretion systems, and recombinant protein fusion partners. Although, the protocol is rather simple for soluble proteins, heterologous protein expression is frequently encountered by major technical limitations including inefficient translation, formation of insoluble inclusion bodies, lack of posttranslational modification mechanisms, degradation by host proteases, and impaired cell physiology due to host/protein toxicity, in achieving functional expression of stable, soluble, and bioactive protein.. In this thesis, model protein expression systems are used to address the technical issues for enhancing recombinant protein expression in E. coli. When yellow fluorescence protein (YFP) was displayed on E. coli cell surface, the integrity of the cell envelope was compromised and cell physiology was severely impaired, resulting in poor display performance, which was restored by the coexpression of Skp, a periplasmic chaperone. On the basis of monitoring the promoter activities of degP, rpoH, and cpxP under various culture conditions, it was demonstrated that the cell-surface display induced the σE extracytoplasmic stress response, and PdegP::lacZ was proposed to be a suitable “sensor” for monitoring extracytoplasmic stress. Intracellular proteolysis has been recognized as one of the key factors limiting recombinant protein production, particularly for eukaryotic proteins heterologously expressed in the prokaryotic expression systems of E. coli. Two amino acids, Leu149 and Val223, were identified as proteolytically sensitive when Pseudozyma antarctica lipase (PalB) was heterologously expressed in Escherichia coli. The functional expression was enhanced using the double mutant for cultivation. However, the recombinant protein production was still limited by PalB misfolding, which was resolved by DsbA coexpression. The study offers an alternative genetic strategy in molecular manipulation to enhance recombinant protein production in E. coli. To overcome the technical limitations of protein misfolding, ineffective disulfide bond formation, and protein instability associated with intracellular proteolysis in the functional expression of recombinant Pseudozyma antarctica lipase B (PalB) in Escherichia coli, an alternative approach was explored by extracellular secretion of PalB via two Sec-independent secretion systems, i.e. the α-hemolysin (Type I) and the modified flagellar (Type III) secretion systems, which can export proteins of interest from the cytoplasm directly to the exterior of the cell. Bioactive PalB was expressed and secreted extracellularly either as HlyA fusion (i.e. PalB-HlyA via Type I system) or an intact protein (via Type III system) with minimum impact on cell physiology. However, the secretion intermediates in the intracellular fraction of culture samples were non-bioactive even though they were soluble, suggesting that the extracellular secretion did mediate the development of PalB activity. PalB secretion via Type I system was fast with higher specific PalB activities but poor cell growth. On the other hand, the secretion via Type III system was slow with lower specific PalB activities but effective cell growth. Functional expression of lipase from Burkholderia sp. C20 (Lip) in various cellular compartments of Escherichia coli was explored. The poor expression in the cytoplasm was improved by several strategies, including coexpression of the cytoplasmic chaperone GroEL/ES, using a mutant E. coli host strain with an oxidative cytoplasm, and protein fusion technology. Fusing Lip with the N-terminal peptide tags of T7PK, DsbA, and DsbC was effective in boosting the solubility and biological activity. Non-fused Lip or Lip fusions heterologously expressed in the periplasm formed insoluble aggregates with a minimum activity. Biologically active and intact Lip was obtained upon the secretion into the extracellular medium using the native signal peptide and the expression performance was further improved by coexpression of the periplasmic chaperon Skp. The extracellular expression was even more effective when Lip was secreted as a Lip-HlyA fusion via the α-hemolysin transporter. Finally, Lip could be functionally displayed on the E. coli cell surface when fused with the carrier EstA.